Process for the production of hydrogen sulphide



Patented Nov. 14, 1922.

ASSIGNOR TO THE GRAS SELLI CHEMICAIi COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO.

PROCESS FOR THE PRODUCTION OF HYDROGEN SULPHIDE.

.No Drawing.

To all whom it may concern:

Be it known that I, HENRY HOWARD, a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in Processes for the Production of Hydrogen Sulphide, of which the following is a specification.

This invention relates to theproduction of hydrogen sulphide, the process being particularly adapted to the production of hydrogensulphide in large quantities for com;

mercial purposes in which a simple continu,

ous process, the use of cheap reagents and high yields are essential. The process may .of course be used for the production of hydrogen sulphide on a .small scale, for in-. stance, for laboratory use,"if desired.

The process broadly consists in treating a metal sulphide, such as zinc sulphide and more particularly a zinc sulphide orewith sulfuric acid whereby hydro en sulphide is generated according to the ollowing reaction.

The ordinary commercialmethod of generating hydrogen sulphide is" by the treatment of iron sulphide with sulfuric acid. This process is satisfactory for the production of small quantities of hydrogen sulphide, for instance, for use in chemical laboratories and in the de-arsenication of sulfuric acid, but when considerable quantities of hydrogen sulphide are required the cost of the process is prohibitive.

It has been proposed according to the so- I called Christensen process to treat complex furic acid that is, about 50 pounds of 52 B.

sulphide ores containing zinc sulphide with sulfuric acid. A feature of this process is the use of a relatively large quantity of sulsulfuric acid to one pound of ore. With this ratio of acid to ore and at high temperature the zinc sulfate formed is dissolved in the large'excess of acid from which it is enable the zinc sulfate to be brought into solution as it forms, the theory being that if it were not so dissolved it would form" a coating over the ore and thereby prevent further reaction. The process is not ,a com- Application filed October 20, 1921. Serial No. 509,216.

mercial success owing to the enormous vol- .umes of sulfuric acid required to be handled and the veryexpensivc heat interchangers necessary for heating and cooling the same. I have based my process. upon the-theory that if the sulphide ore were ground sufficiently fine and then kept agitated in admixture. with the acid, the reaction could be carried to'substantial completion without dlssolv ng the zinc sulfate formed in the react1on.

My process-is carried out as follows: Sulfuric acid of about 52 B. is run into I a lead-lined'tank provided with .a tight cover and efiicient stirring means. The acid is heated to about 190 C. and pulverized zinc sulphide ore is slowly fed in by means of an automatic. and continuousfeeding de-; vice, the contents of the tank being continuously stirred. The decomposition is almost instantaneous producing a steady and continuous "evolution, of hydrogen sulphide the flow of which is controlled by controlling the feed 'ofore. As stated above the ore must be finely ground. I have tried the use of'ore that would all pass through a 200 mesh screen and. havethereby obtained a yield of from to per cent of hydrogen sulphide calculated upon the sulfur content of the ore while 97% of the zinc sulphide content of the ore was converted into, zinc sulfate; The loss of hydrogen sulphide has been found to be due largely to the formation of 'elemeIrtal sulfur; f

About five pounds of sulfuric acid are used for one-pound of ore rich in sulphides. It -wi1l be understood however that the ratio of acid to ore may be varied. within a considerable range without departing from my invention. Itisonly necessary to use suflicient acid to cause the reaction to proceed to substantial completion and theamount of acid re uired for any particular ore inay be easily etermined.

After the requisite. amount of ore has been fed in to a batch of acid the stirring is continued and the mixture boiled until evolution .of ,.hydrogen sulphide is complete, whereupon. the stirrer i'systopped. and the. 105 batch cooled and allowed to settle. The supernatant acid which is still about 52 B is siphoned off .and mixed with fresh acid* and used again for the treatment of another batchof ore. The acid thus recovered and 110 solution is neutralized by the addition of zinc oxid or zinc cinder and the zinc sulfate solution after separation from the undissolved residue, and purification in the ordinary well known manner, is available for use or sale as maybe desired.

'It will be seen that by my process hydrogen sulphide is cheaply and efficiently produced, in large quantities if desired, and

that in the recovery of the zinc content of the ore the co'stof the customary roasting" of the ore and the loss of zinc resulting from the formation of ferrites and silicates which are insoluble in acid/are obviated.

llQ-claim: i 1. Process for the production of'hydrogen sulphide which. comprises, mixing zinc sulphide with sulfuric acid in quantity insufiicient to dissolve all ofthe zinc sulfate formed by the interaction of the zinc sulphide with the sulfuric acid, and. agitating and heating the mixture. v

'2. Process for the production of hydrogen sulphide which comprises, heating and agitating a mixture of pulverized zinc sulphide ore with sulfuric acid whereby hydrogen sulphide is evolved and zinc sulfate ,is formed, the sulfuric acid in said mixture being insuflicient to dissolve all of said zinc sulfate. i v q 3. Process for the production -of hydrogen sulphide which comprises, heating a body of sulfuric acid, feeding pulverized zinc sulphide ore" into said acid with continuous agitation of the resulting mixture, and conresulting slurry, and mixin geri sulphide which comprises, mixing sulfuric acid with pulverized zinc sulphide ore in approximately the ratio of 5 parts by Weight of acid to 1 part by weight of ore, heating and agitating the mixture until the evolution of hydrogen sulphide substantially ceases, separating sulfuric acid from the said separated acid with a further quantity 'of-zinc sulphide ore in a succeeding repetition of the process,

5. Process for the production of hydrogen sulphide which comprises, heating a body of sulfuric acid of about 52 B. to a temperature of 190 0., and while maintaining said temperature'feeding zinc sulphide ore pulverized to pass a 200 mesh screen into said body of sulfuric acid with continuous agitation until one part by weight of ore to 5 parts by weight of said body of acid has been fed in, heating and agitating the mixture, separating sulfuric acid from the resulting slurry, mixing said separated acid with fresh acid, and feeding pulverized zinc sulphide ore into said mixed acid in a succeeding repetition of the process.

6. Process for the production of hydrogen sulphide which comprises, mixing zinc sulphide ore pulverized to 200 mesh with sulfuric acid of 521 B., and heating and agitating the mixture.

7. Process for the'production of Hydrogen- I sulphide which comprises, mixing one part by weight of zinc sulphide ore pulverized to 200 mesh with 5 parts by weight of sulfuric acid of 52 Be. at a temperature of 190 (3., and heating and agitating the mixture. e

In testimony whereof, I afix my'signa-\ ture.

Q RY HOWARD. 

